so i spent 3 days looking for errors on my pcb's, everything cheked out ok.
Then i decided to investigate the lm394 and found there were no transistors inside. So either i blew them up or i think i have some fake 394's. I have ordered a coupe more from different sources and this time i will measure them before i put them in.

So it seems i was sold some fake LM394's as i put in a fresh one from little diode (after measuring it with my Peak Atlas DCA inwich read each side of the ic
as NPN Darlington) and i was rewarded with a lovely lookin Sawtooth.

Reminds me of an old PC motherboard I had way back when the cache was on separate chips from the CPU. After upgrading the MB I took one of the cache chips apart and they were empty inside! Nothing but a plastic case holding metal pins. Pretty irritating.

In my digital logic lab in college we would pop TTL chips all the time. Pretty frustrating when you don't know if the problem is with your circuit or a bad IC. Sensitive little suckers.

I've only used discreet transistors in my VCO's but still wonder how much of a difference the 394's make. I can hear them drifting a bit when two are played together but I haven't epoxied them together with the tempco yet. Hopefully that will improve things a bit but maybe I should give the 394 a try._________________My synth build blog: http://gndsynth.blogspot.com/

I built 2 units both with lm394's and can say both are rock solid. I would like to know the expected current draw of this vco, it doesn't seem to say on the yusynth web site. Do you have a figure Yves?

Now I have calibrated all my oscillators ( 2x yusynth, 2x system X and 2x hearn morely) against the CV Standard module I can play all 6 oscillators with 1 cv line.......heaven!

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